Abstract Psychosocial adversity and African-American ethnicity are both associated with increased risks for cardiovascular disease. This study examines possible underlying mechanisms of such increased risk and also examines how ethnicity and adversity interact in determining such risks. Specifically, this application proposes to scrutinize how ethnicity and adversity are related to blood pressure regulation, sleep, inflammatory markers, and the autonomic nervous system. One hundred African-American and 100 Euro-American subjects will be enrolled. Subjects will be either healthy volunteers or hypertensives not receiving anti-hypertensive therapy. Subjects will be admitted to the General Clinical Research Center for a 2-night stay during which they will complete overnight polysomnography, reactivity testing, and endothelial function testing. Vasoactive agonists will be infused and/or inhaled to assess baroreflex functioning, beta-adrenergic sensitivity, and vasodilatory response. Biochemical determinations will be made of their sympathetic nervous system functioning, as well as inflammatory response at rest and after exposure to short-term stressors. Subjects will complete questionnaires characterizing their exposure to stressors and their psychosocial functioning. They will also complete outpatient ambulatory blood pressure monitoring. This research will study mechanisms by which adversity increases cardiovascular risk. The study scrutinizes sleep, inflammation, vasodilation, autonomic functioning, and baroreflex regulation. We hypothesize that adversity has a stronger impact on cardiovascular pathophysiology than does ethnicity. Keywords: hypertension, ethnicity, sleep, inflammation, sympathetic nervous system, social class